Servomotors for power actuation are known which comprise a housing in which a power piston separates a low pressure chamber from a high pressure chamber. The power piston being movable from an idle position in response to an input force to establish a pressure difference between the two chambers. The pressure difference is controlled by movement of the control valve associated with an inlet control member.
Servomotors of this type are associated with many mechanical or hydraulic controls, such as master cylinders for motor vehicles. Such servomotors are operated by movement of a push rod associated with a brake pedal located in a vehicle. In addition to such power actuated brake systems, most vehicles have emergency brake systems which are independently operated by the operator.